Asymmetric phase transfer catalysis has been recognized as a convenient and powerful methodology in organic chemistry. This synthetic approach provides many advantages, including simple procedure, mild conditions, suitability for large scale reactions, and safety.
Various chiral phase transfer catalysts have been developed in the past thirty years, e.g., N-alkylated cinchomimium halide and N-spiro chiral ammonium salt. See O'Donnell et al., J. Am. Chem. Soc., 1989, 111, 2353; Ooi et al., J. Am. Chem. Soc., 1999, 121, 6519.
Yet, there is a need for less expensive and more efficient chiral phase transfer catalysts.